Sodium tanshinone IIA sulfonate (STS) is a water-soluble derivative of tanshinone IIA isolated as the main pharmacologically active natural compound from a traditional Chinese herbal medicine,the dried root of Salvia miltiorrhiza Bunge known as Danshen. Danshen has been known for the function of improving body functions such as activating blood circulation and removing blood stasis according to the theory of traditional Chinese medicine. Danshen and its various formula products including STS have been long-time widely used in oriental countries, especially China to treat various inflammatory and cardiovascular diseases for its pharmacological actions, including vasodilatation, anticoagulation, anti-inflammation, and free radical scavenging,with negligible adverse effects observed.

The investigator's objective is to evaluate whether STS exhibits beneficial effects on pulmonary hypertension. This is a randomized, controlled, multicentre clinical trial study. 90 patients with pulmonary hypertension will be enrolled in this study.

Inclusion Criteria:

1. Meet the condition of mean pulmonary arterial pressure (mPAP) ≥25 mmHg at seal level at rest and pulmonary capillary wedge pressure(PCWP)≤15mmHg;
2. Category 1 or 4 of PH in stable stage according to 2008 Dana Point Conference,including the idiopathic, hereditary, drugs and toxins induced, associated with connective tissue disease or congenital heart disease, and chronic thromboembolic pulmonary arterial hypertension(PAH) ;
3. Male or female between 15 to 70 years old;
4. WHO pulmonary hypertension functional class II or III;
5. The baseline 6-minute walk distance between 150-550 m;
6. Patients' condition should be stable for more than one month after basic treatment; For those patients with congenital heart disease, surgery should have been performed six months or more before they are enrolled in the study;
7. Patients receiving sildenafil treatment only previously, or those without target drugs treatment during the past 3 months;
8. Patients or their guardians should agree with this clinical trail and medical informed consent of the trial should be signed.

Exclusion Criteria:

1. Unavailable or limited legal capacity;
2. Pregnant or lactational women;
3. Important organs with severe diseases;
4. Mental or physical disability;
5. With suspected or indeed alcohol, drug abuse history;
6. With allergic constitution, with two or more drugs or foods allergy history or those who are allergic to any components of the experimental drugs;
7. With both aspartate aminotransferase (AST) and glutamic-pyruvic transaminase (ALT) more than three times of the upper limit of normal in liver function test and Ccr≤50ml/min in kidney function test;
8. Those with systemic blood pressure<90/50 mmHg, or those uncontrolled dangerous hypertension(BP>170/110 mmHg);
9. Patients at active stages of infectious or other diseases such as hepatitis A, hepatitis B, AIDS, tuberculosis, and some connective tissue diseases;
10. Patients with severe infection, especially pulmonary infection;
11. Patients with shock or astable hemodynamics with other causes;
12. Patients with hepatic cirrhosis, and hepatic cirrhosis induced portal hypertension;
13. Patients with severe hemorrhage, and hemorrhagic tendency;
14. Patients who need to take or be taking drugs possible or indeed affecting this trial;
15. Patients cannot accomplish required items (especially 6MWD) because of acute/chronic organic disease (excluding dyspnea) or other illnesses such as lower extremity diseases;
16. Patients with any other conditions considered cannot be recruited.